Bob Demers
>Bill

That could be difficult, if not very laborious, read expensive.
These dado's planes have a skew iron and a somewhat overly shaped lever cap. Its bottom width, being determined by the actual width of your particular size dado plane.
See link for sample pictures

As with most antique tools, the one with missing parts are never bargains, as the elusive replacements parts are often hard to find and when found, expensive. Always cheaper in the end to buy complete specimen.

Best to consider that plane as 'donor' plane, broken down and sold for parts
PS the depth stop is often missing or broken

Bob